Tips for Telescope Buying

One of the most common questions we get at the Phoebe Waterman Haas Public Observatory is about what kind of telescope to buy, whether for a gift or for personal use. In the height of the holiday shopping, we’re here to help answer that question.

A young visitor observes Jupiter through the 85mm refracting telescope at the Public Observatory. Photo by Eric Long, Smithsonian

First, a question for you: Are you a novice sky gazer? In that case, don’t buy a telescope just yet! Telescopes are not a good way to learn your way around the night sky. Often, they can be frustrating if you get one before you’re ready. We recommend starting with a sky map. Learn some of the constellations, watch for meteors and satellites, and find the Milky Way. Another great resource is your local observatory or amateur astronomy club. They likely have regular stargazing events, which are a great time to try out different telescopes and ask advice from knowledgeable and enthusiastic people. Binoculars are a great “first telescope.” They are portable and easy to use and can reveal surprising detail on the Moon and planets. In fact, many celestial sights like comets and star clusters look better with binoculars than with a telescope! The numbers on the binoculars will tell you the magnification and the size of the lenses. For example, a 10x50 pair of binoculars has 10x magnification and lenses 50mm in diameter. Look for high optical quality, magnifications between 7x and 10x and lenses at least 35mm in diameter. If you’re feeling ready for a telescope, do your research. Online reviews and local astronomers are a great source of information. The “best” telescope is one that suits your needs. Here’s some general guidance:

Most telescopes that cost less than $300 aren’t really worth it. We suggest getting good binoculars instead.

Stay away from any telescope advertised for its magnifying power.

For a child, look for a tabletop telescope that’s portable, easy to push around the sky, and virtually indestructible.

A telescope’s most important attribute is its size, meaning the diameter of its main mirror or lens. The bigger the telescope, the more light it collects, which allows you to see dimmer objects.

A popular first telescope is a Dobsonian. These easy-to-use telescopes offer large apertures for relatively low prices. The mount is simple to point and adjust; that’s why John Dobson designed it that way!

Telescopes need a mount, like a sturdy tripod or a Dobsonian base, to hold it for observing. Make sure it’s a solid mount to avoid shaky views. If it has knobs that turn slowly to adjust where the telescope is pointed, that will help you to follow objects across the sky.

Once you have your telescope, what will you observe with it? The Moon is a great first target, especially when it’s half-lit. Look for craters along its shadow line. Next, try the brighter planets: Jupiter, Saturn, Venus, and Mars. The moons of Jupiter and the rings of Saturn are an incredible sight. More advanced targets include the Orion Nebula, the Andromeda Galaxy, and binary stars like Albireo. An astronomy guide, star map, or smartphone app can help you find what to hunt for next. You can find an astronomy club, get sky maps, look up what can be observed from your area, and more on NASA’s Night Sky Network page. You can also email us your questions at SIObservatory@si.edu. We can’t recommend any specific brands, but we are happy to give general advice. You can also try out lots of telescopes at our Public Observatory’s stargazing night today, December 20, from 6:30 to 8:30 pm. If you miss this event, don't worry. We offer evening observations on a regular basis. See a listing of all of our upcoming events.